Emergency services were called to North Curl Curl, in Sydney's Northern Beaches, about 4.30pm on Monday after reports of a crash.
Police said the altercation began when a driver of a Volkswagen SUV allegedly made an offensive hand gesture to a group of teenage e-bike riders.
The driver, a 38-year-old man, then drove away before one of the teens, a 15-year-old boy, followed and engaged in a verbal argument with the driver.
During the argument, the driver allegedly threw a water bottle at the teen before driving away.
The 15-year-old then threw the same water bottle back at the car, but it did not make an impact, police said.
The boy continued to follow the car before blocking it at the intersection of Abbott and Pitt roads.
The 38-year-old then allegedly drove into the boy, causing him to be thrown from the e-bike.
Police allege the man drove away from the scene and failed to stop when two nearby off-duty officers directed him to do so.
Paramedics treated the 15-year-old for serious leg injuries before taking him to Randwick Children's Hospital in a serious but stable condition.
A crime scene was established and detectives commenced an investigation.
Following inquiries, the 38-year-old was arrested at Dee Why Police Station about 5.30pm.
He was transferred to Manly Police Station and charged with driving furiously in a motor vehicle to cause bodily harm, negligent driving (no death or grievous bodily harm) and driving while licence application has been refused.
He was granted strict conditional bail to appear before Manly Local Court on Wednesday.
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